Cell Relay Archive

[R Wilcox <nulldevice@eli.net>]

This is a hot topic of discussion within the ATM Forum now.
Several documents offering guidance and reference material
are awaiting approval. There is also a longer term "bilevel
addressing" proposal which allocates the higher order bits
to the carrier and the lower order bits to the enterprise in a
standard way such that the lower order bits are "portable"
(as in local number portability).

Some general guidelines:

It is recommended that enterprises obtain addresses from
their carrier to minimize route fragmentation. The Internet,
with 50K+ routes, is an example of route fragmentation.
Note that the trend in the Internet is for enterprises to get
IP addresses from carriers too.

E.164 addresses are primarily designed for carrier networks
not recomended, and probably not available to enterprises.
Your carrier may assign some to you, but there is somewhat
a shortage of them too.

For US enterprises and carriers, the DCC format addresses
allow 6 bytes to be split between the carrier and customer
routing heirarchy.

The ICD format has 10 bytes available to be split between
the carrier and the enterprise. These are assigned by the
British Standards Institute on behalf of ISO.

You will need to negotiate with your carrier on the allocation
of bits in the address between carrier routing and your internal
enterprise routing.

If you are extremely large, like the US Department of Defense,
there is more of an argument for acquiring your own address space.

Production SVC service is still a bit rare. ATT in the US has it
now. Many carriers plan it later in the year. There are few (to
none) carrier interconnection agreements for PVC's, and none
for SVC's I know of. The usual method is SVC tunneling.

Your enterprise numbering should be topologically significant within
its own ATM routing domain.As well it should be one format.

If you obtain carrier addresses, or even if you use your own,
you may need to renumber in the future. ILMI address registration
helps.

R. Wilcox
Electric Lightwave





Doug McClure wrote:

> I'm doing research on the different ATM addressing schemes for a planned large
> backbone ATM network.
>
> What ATM address method should be used?  Private E.164, DCC, and ICD or native
> E.164?  If the network connected to a public ATM carrier, what would I have to
> use?  I assume I would have to use the standard they're using.  Is there a
> standard addressing scheme for all public ATM carriers? What do domestic ATM
> carriers (MCI/ATT/Sprint/UUNet/WorldCom, etc) use for ATM addressing formats?
> Should address space be acquired or just delegated from the upstream provider?
>
> If the backbone network is a mesh of private links and public links, what are
> the recommended addressing formats to use?  Should it be consistent across the
> network?  If the network is all private, what format should be used?  All
> public?
>
> Are there advantages/disadvantages in addressing a large scale ATM backbone in
> one format vice another?
>
> Thanks for any pointers, links and advice.
>
> Doug